CN114195628B - Acetaldehyde purifying device and technology thereof - Google Patents
Acetaldehyde purifying device and technology thereof Download PDFInfo
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- CN114195628B CN114195628B CN202111669665.8A CN202111669665A CN114195628B CN 114195628 B CN114195628 B CN 114195628B CN 202111669665 A CN202111669665 A CN 202111669665A CN 114195628 B CN114195628 B CN 114195628B
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- acetaldehyde
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- vinyl acetate
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- IKHGUXGNUITLKF-UHFFFAOYSA-N Acetaldehyde Chemical compound CC=O IKHGUXGNUITLKF-UHFFFAOYSA-N 0.000 title claims abstract description 690
- 238000005516 engineering process Methods 0.000 title abstract description 3
- 238000007670 refining Methods 0.000 claims abstract description 264
- 238000000605 extraction Methods 0.000 claims abstract description 186
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 claims abstract description 152
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 114
- 239000007788 liquid Substances 0.000 claims abstract description 76
- 238000005065 mining Methods 0.000 claims abstract description 35
- 238000004821 distillation Methods 0.000 claims abstract description 17
- 239000012071 phase Substances 0.000 claims description 35
- 238000000034 method Methods 0.000 claims description 34
- 230000008569 process Effects 0.000 claims description 26
- 238000000926 separation method Methods 0.000 claims description 20
- 239000010865 sewage Substances 0.000 claims description 19
- 238000011084 recovery Methods 0.000 claims description 14
- 239000007791 liquid phase Substances 0.000 claims description 9
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 claims description 8
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 claims description 8
- 239000002994 raw material Substances 0.000 claims description 6
- 238000001816 cooling Methods 0.000 claims description 5
- 238000007789 sealing Methods 0.000 claims description 5
- 238000003786 synthesis reaction Methods 0.000 claims description 5
- 238000000746 purification Methods 0.000 claims description 4
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- 238000010992 reflux Methods 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 claims description 2
- 239000003795 chemical substances by application Substances 0.000 claims description 2
- 230000002194 synthesizing effect Effects 0.000 claims description 2
- 238000009833 condensation Methods 0.000 claims 1
- 230000005494 condensation Effects 0.000 claims 1
- 230000000694 effects Effects 0.000 abstract description 20
- 238000005265 energy consumption Methods 0.000 abstract description 7
- 238000010438 heat treatment Methods 0.000 abstract description 6
- 239000007789 gas Substances 0.000 description 27
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 21
- IKHGUXGNUITLKF-XPULMUKRSA-N acetaldehyde Chemical compound [14CH]([14CH3])=O IKHGUXGNUITLKF-XPULMUKRSA-N 0.000 description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 8
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 6
- ZOIORXHNWRGPMV-UHFFFAOYSA-N acetic acid;zinc Chemical compound [Zn].CC(O)=O.CC(O)=O ZOIORXHNWRGPMV-UHFFFAOYSA-N 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 239000004246 zinc acetate Substances 0.000 description 6
- 239000012295 chemical reaction liquid Substances 0.000 description 5
- 238000006116 polymerization reaction Methods 0.000 description 4
- 238000003466 welding Methods 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 239000003054 catalyst Substances 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 230000002035 prolonged effect Effects 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- 239000002918 waste heat Substances 0.000 description 3
- 229920001744 Polyaldehyde Polymers 0.000 description 2
- 230000001174 ascending effect Effects 0.000 description 2
- 238000010612 desalination reaction Methods 0.000 description 2
- 239000000284 extract Substances 0.000 description 2
- 239000000706 filtrate Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000002351 wastewater Substances 0.000 description 2
- JTXMVXSTHSMVQF-UHFFFAOYSA-N 2-acetyloxyethyl acetate Chemical compound CC(=O)OCCOC(C)=O JTXMVXSTHSMVQF-UHFFFAOYSA-N 0.000 description 1
- 239000005997 Calcium carbide Substances 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000011033 desalting Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000012958 reprocessing Methods 0.000 description 1
- 235000011121 sodium hydroxide Nutrition 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- CLZWAWBPWVRRGI-UHFFFAOYSA-N tert-butyl 2-[2-[2-[2-[bis[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]amino]-5-bromophenoxy]ethoxy]-4-methyl-n-[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]anilino]acetate Chemical compound CC1=CC=C(N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)C(OCCOC=2C(=CC=C(Br)C=2)N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)=C1 CLZWAWBPWVRRGI-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/78—Separation; Purification; Stabilisation; Use of additives
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/78—Separation; Purification; Stabilisation; Use of additives
- C07C45/80—Separation; Purification; Stabilisation; Use of additives by liquid-liquid treatment
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/78—Separation; Purification; Stabilisation; Use of additives
- C07C45/81—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
- C07C45/82—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
Abstract
The invention relates to an acetaldehyde purifying device and a technology thereof. The device comprises: extraction tower, acetaldehyde refining tower middle extraction groove, middle extraction separator and middle extraction heat exchanger. In the device, the height of the middle-mining separator and the arrangement of three baffle plates increase the residence time of the middle-mining liquid, improve the layering effect, lead the middle-mining separator to extract the upper liquid of the vinyl acetate, lead the lower acetaldehyde water to return to the lower column plate of the acetaldehyde refining column, and reduce the extraction amount of the acetaldehyde water, thereby reducing the energy consumption; the temperature of the liquid extraction in the acetaldehyde refining tower is reduced to 5-15 ℃ through a middle heat exchanger, and the liquid is further layered in a distillation tank of the acetaldehyde refining tower and then enters the tower kettle of the extraction tower, so that the temperature of the tower kettle of the extraction tower is reduced to 10-15 ℃ from 25-30 ℃, and the extraction effect of the extraction tower is improved; the tower bottom of the acetaldehyde refining tower is directly fed with steam for heating, so that the problem that the reboiler is blocked to influence the stable supply of heat is solved, the stable operation of the acetaldehyde refining tower is ensured, and the equipment investment is reduced.
Description
Technical Field
The invention belongs to the field of chemical equipment, and particularly relates to an acetaldehyde purifying device and an acetaldehyde purifying process.
Background
At present, the preparation method of vinyl acetate mainly comprises two processes of an ethylene method and an acetylene method, wherein the process for producing vinyl acetate by the acetylene method mainly comprises two processes of fluidized bed and fixed bed gas phase synthesis. The technological process of synthesizing vinyl acetate in fluidized bed gas phase includes the reaction of mixed gas of acetylene and acetic acid in fluidized bed reactor with active carbon as carrier and zinc acetate as catalyst at certain temperature, separating catalyst powder in powder separator, separating the catalyst powder, gas separating in gas separating tower to obtain the second stage synthesis reaction liquid, first stage extraction of active carbon powder filtrate with great amount of zinc acetate, and rectification and filtering to obtain the filtrate. After the synthesis reaction liquid and the filtered clear liquid are treated by a vinyl acetate rough separation tower, the material at the bottom of the tower is further refined to obtain vinyl acetate, the material at the top of the tower contains vinyl acetate, acetaldehyde and water, and the material enters an extraction tower and an acetaldehyde refining tower to be refined to obtain the product acetaldehyde. Wherein, in order to recycle the vinyl acetate in the acetaldehyde refining tower, the ethylene acetate can be obtained by separating the liquid produced in the middle part of the acetaldehyde refining tower. Because the middle produced liquid of the acetaldehyde refining tower contains acetaldehyde, vinyl acetate and water, if the middle produced liquid is directly produced in a gas phase, the following problems exist: firstly, the extraction quantity is large; secondly, the temperature of the liquid in the acetaldehyde refining tower is 35-60 ℃, so that the water separation of vinyl acetate and acetaldehyde in the liquid is difficult, and the liquid is directly sent into the extraction tower to influence the extraction effect of the extraction tower. If the middle liquid is directly extracted and cooled to 5-15 ℃ to separate the vinyl acetate and the acetaldehyde water and then the vinyl acetate is recovered by rectification again, a large amount of cold energy is required, and the energy consumption is increased. In addition, the acetaldehyde refining tower related in the technical process adopts a reboiler for heat exchange and heating, and vinyl acetate or polyaldehyde in the feeding is easy to block the reboiler, so that the heat exchange effect is affected, and the stable operation of the acetaldehyde refining tower is also affected. In addition, the extraction tower needs a large amount of desalted water as an extractant to separate acetaldehyde and vinyl acetate, the operation temperature of the extraction tower is lower and is 5-15 ℃, the normal temperature of the desalted water is 25-35 ℃, and a large amount of chilled water is needed for cooling, otherwise, the extraction effect of the extraction tower is affected; in addition, the use of demineralized water can also result in a significant amount of wastewater being produced at the bottom of the extraction column.
Disclosure of Invention
The first technical problem to be solved by the invention is that the liquid extraction amount in the acetaldehyde refining tower is large, and the layering of vinyl acetate and water in the liquid extraction is difficult due to the high temperature of the liquid extraction, so that a large amount of cold energy is needed to cool the liquid extraction to 5-15 ℃ to laminate the vinyl acetate and water, and then the vinyl acetate is recovered by rectification again, thus finally increasing the energy consumption. The second technical problem to be solved by the invention is that the reboiler is heated by adopting the reboiler, and the reboiler is blocked by vinyl acetate or polyaldehyde in the feeding, so that the heat exchange effect is affected, and the stable operation of the acetaldehyde refining tower is affected. The third technical problem to be solved by the invention is that a large amount of desalted water is needed as an extractant for separating acetaldehyde from vinyl acetate, a large amount of chilled water is needed for cooling the desalted water, if the temperature is not lowered, the extraction effect of the extraction tower is affected, and a large amount of sewage is generated at the bottom of the extraction tower by using the desalted water. To this end, the present invention provides an acetaldehyde purifying apparatus, and further provides an acetaldehyde purifying process using the same.
The invention is realized by the following technical scheme:
in a first aspect, the present invention provides an acetaldehyde purification apparatus comprising: the device comprises an extraction tower, an acetaldehyde refining tower, a first condenser of the acetaldehyde refining tower, a second condenser of the acetaldehyde refining tower, an acetaldehyde refining tower distillation tank, an acetaldehyde refining tower middle-mining tank, a sewage treatment system, a middle-mining separator and a middle-mining heat exchanger;
wherein the tower top distillate pipeline of the vinyl acetate crude separation tower is connected with the lower inlet of the extraction tower, the upper inlet of the extraction tower is connected with the synthetic acetaldehyde water pipeline, the bottom outlet of the extraction tower is connected with the inlet of the acetaldehyde refining tower, the recovery liquid pipeline of the extraction tower at the upper outlet of the extraction tower is connected with the inlet of the vinyl acetate crude separation tower, the top outlet of the acetaldehyde refining tower is connected with the inlet of the first condenser of the acetaldehyde refining tower, the bottom outlet of the acetaldehyde refining tower is connected with the sewage treatment system, the upper outlet of the first condenser of the acetaldehyde refining tower is connected with the gas phase inlet of the second condenser of the acetaldehyde refining tower, the condensate outlet pipeline of the first condenser of the acetaldehyde refining tower is connected with the condensate outlet pipeline (preferably after being converged) of the second condenser of the acetaldehyde refining tower, the outlet pipeline of the distillation tank of the acetaldehyde refining tower is divided into two paths, one path is connected with the acetaldehyde pipeline, the other path returns to the top of the acetaldehyde refining tower, the middle part of the acetaldehyde refining tower is provided with a middle extraction separator for middle liquid phase extraction, the acetaldehyde water outlet (lower water phase outlet) of the middle extraction separator returns to the acetaldehyde refining tower, the vinyl acetate liquid outlet (upper outlet) of the middle extraction separator is connected with the inlet of the middle extraction heat exchanger, the outlet of the middle extraction heat exchanger is connected with the top inlet of the middle extraction tank of the acetaldehyde refining tower, the upper outlet of the middle extraction tank is connected with the lower inlet of the extraction tower through the pipeline, and the bottom outlet of the middle tank is connected with the sewage treatment system. Preferably, the tower bottom of the acetaldehyde refining tower is connected with a steam inlet pipeline.
Preferably, the intermediate recovery separator is disposed at the 25 th to 30 th trays, more preferably at the 29 th to 30 th trays, of the acetaldehyde refining column.
Preferably, a pipe cap is arranged at the 25 th-30 th tower plate of the acetaldehyde refining tower, one circle of pipe cap bottom is connected with the acetaldehyde refining tower in a sealing way, and one side opening of the tower wall connected with the connection part of the acetaldehyde refining tower is connected with a middle-collecting separator.
Preferably, the height of the mesogenic separator is 800-1000mm, for example about 912mm.
Preferably, the middle-mining separator adopts three baffles, the first baffle is arranged at the top of the inner side of the middle-mining separator, the second baffle is arranged at the bottom of the inner side of the middle-mining separator, the third baffle is arranged at the top of the inner side of the middle-mining separator, and the second baffle is crossed with the first baffle and the third baffle (preferably, the first baffle, the second baffle and the third baffle are all vertically arranged), so that the effect of layering vinyl acetate and acetaldehyde is achieved. The middle-layer extraction separator of the acetaldehyde refining tower controls layering of vinyl acetate and acetaldehyde water through 3 layers of baffle plates, namely three baffle plates, and the upper-layer vinyl acetate liquid after layering enters the middle-layer extraction heat exchanger and then enters the middle-layer extraction groove of the acetaldehyde refining tower, and the lower-layer acetaldehyde water returns to the acetaldehyde refining tower. A pipe cap is added in the position of 25-30 layers of tower plates in the acetaldehyde refining tower, one circle of the bottom of the pipe cap is in sealing connection with the acetaldehyde refining tower, one side of the tower wall connected with the connection position of the acetaldehyde refining tower is connected with a middle-collecting separator, and all condensed liquid falling from the upper layer of tower plates (for example, 30 layers) where the pipe cap is positioned is ensured to enter the middle-collecting separator. The gas phase continues to rise from the pipe cap, condensed liquid is extracted and flows into the middle extraction separator, the liquid reaches the first baffle plate water phase and flows into the second baffle plate through the lower gap of the baffle plate, after the middle liquid reaches the upper edge of the second baffle plate, the layering time is prolonged due to the action of the baffle plate, the upper layer of vinyl acetate liquid overflows into the third baffle plate after layering, the upper layer of vinyl acetate liquid is extracted through the interface regulator and the middle outlets of the second baffle plate and the third baffle plate, and the lower layer of acetaldehyde water returns to the lower layer of tower plate (for example, 29 layers) of the acetaldehyde refining tower after passing through the third baffle plate, so that the layering effect is ensured, and the extraction amount of the acetaldehyde water is reduced. Namely, the ascending air flow enters a 30-layer tower plate for example through a pipe cap, the condensed liquid is layered through a middle-collecting separator, the interface height of the upper-layer vinyl acetate liquid and the lower-layer acetaldehyde water is adjusted by a middle-collecting interface regulator, so that the upper-layer vinyl acetate liquid is conveniently collected, the lower-layer water phase (acetaldehyde water) flows back to an acetaldehyde refining tower (for example, a 29-layer tower plate) through an acetaldehyde water outlet, and the upper-layer vinyl acetate is connected with the inlet of a middle-collecting heat exchanger through a pipeline through an ethyl acetate upper-layer liquid outlet.
Preferably, the middle production liquid exchanges heat through a middle production heat exchanger to reduce the temperature.
Preferably, an interface regulator is arranged in the middle mining separator. The layering height of the middle liquid in the middle liquid extraction separator is adjusted by arranging an interface regulator, so that the upper liquid of the vinyl acetate is extracted through an outlet on the middle liquid extraction separator and enters the middle liquid extraction heat exchanger.
Preferably, chilled water is introduced into the medium heat exchanger. The upper liquid (35-60 ℃) of the vinyl acetate enters a middle heat collecting exchanger and is cooled by chilled water, the temperature is reduced to 5-15 ℃, and after the upper liquid is further layered in a distillation tank of an acetaldehyde refining tower, the upper liquid enters an extraction tower kettle to reduce the temperature of the extraction tower kettle from 25-30 ℃ to 10-15 ℃, so that the extraction effect of the extraction tower is improved.
Preferably, the bottom outlet of the extraction column is connected to the inlet of the acetaldehyde refining column after passing through the heat exchanger. Among them, the heat exchanger is preferably a condenser of a vinyl acetate refining tower so as to utilize the waste heat of the gas phase distilled from the vinyl acetate refining tower. Namely: the gas phase discharge pipeline of the top of the vinyl acetate refining tower is connected with the upper inlet of the condenser of the vinyl acetate refining tower, the condensate outlet of the condenser of the vinyl acetate refining tower is connected with the discharge pipeline of the vinyl acetate condensate, the lower inlet of the condenser of the vinyl acetate refining tower is connected with the bottom outlet of the extraction tower, and the upper outlet of the condenser of the vinyl acetate refining tower is connected with the inlet of the acetaldehyde refining tower. The feeding temperature of the acetaldehyde refining tower is increased from 5-15 ℃ to 40-60 ℃ by gas phase heat exchange with the distillation gas phase of the vinyl acetate refining tower, so that the steam consumption of the acetaldehyde refining tower and the circulating water consumption of the vinyl acetate refining tower are reduced.
In a second aspect, the present invention provides an acetaldehyde purification process comprising the steps of: the reaction liquid (the components are acetic acid 45-50%, vinyl acetate 45-50%, acetaldehyde 1.0-2.5%, acetylene 0.8-1.8%, water 0.01-0.1%, a small amount of carbon powder and zinc acetate, the temperature is 10-40 ℃), filtered clear liquid (the components are acetic acid 85-95%, vinyl acetate 5-10%, water 0.01-0.1%, carbon-containing carbon powder and zinc acetate, the temperature is 85-95 ℃) are rectified by a vinyl acetate roughing tower to obtain a vinyl acetate roughing tower top distillate (containing 85-90% of vinyl acetate, 5-10% of acetaldehyde, a small amount of water 1.0-2.0% and the like, the temperature is 5-15 ℃) and then the vinyl acetate roughing tower top distillate is taken as one of raw materials to enter the lower part of an extraction tower. The extraction tower is used for primarily separating acetaldehyde from vinyl acetate, and the feed of the extraction tower comprises a vinyl acetate crude separation tower distillate (the temperature is 5-15 ℃, the distillate contains 85-95% of vinyl acetate, 5-10% of acetaldehyde and a small amount of water of 1.0-2.0% and the like) and a vinyl acetate supernatant (the temperature is 5-15 ℃, the distillate contains 60-80% of vinyl acetate, 10-20% of acetaldehyde, 5-10% of water and the like) which is extracted from an acetaldehyde refining tower and subjected to heat exchange by a middle extraction heat exchanger. The extraction agent acetaldehyde water (low-temperature acetaldehyde water from a synthetic water washing tower, the acetaldehyde content is 2-5 percent, and the temperature is 0-10 ℃), because acetaldehyde is miscible with water, but the solubility of acetaldehyde in vinyl acetate and the solubility of vinyl acetate in water are very low, the distilled liquid of the vinyl acetate rough separation tower is added from the lower part of the extraction tower, the vinyl acetate therein moves upwards with small density, the acetaldehyde therein is gradually dissolved in the acetaldehyde water added from the upper part of the tower, the density is large, the acetaldehyde moves downwards, and two materials alternately pass through a filler in the tower to make countercurrent contact, and the acetaldehyde gradually diffuses into the water and falls on the lower part of the tower. After extraction, the tower bottom components (components: 80-90% of water, 5.0-10.0% of acetaldehyde, 1.0-5.0% of vinyl acetate and 5-15 ℃ of temperature) of the extraction tower and the distilled gas phase of the vinyl acetate refining tower are heated in a condenser of the vinyl acetate refining tower, then the distilled gas phase is fed into the middle part of the acetaldehyde refining tower after the temperature is increased to 40-60 ℃, and the tower top components (components: 80-90% of vinyl acetate, 1.0-5.0% of acetaldehyde, 0.5-1.5% of water and 5-15 ℃ of temperature) of the extraction tower are used as recovery liquid of the extraction tower to be fed into a vinyl acetate rough separation tower. The feeding of the acetaldehyde refining tower is the tower bottom liquid of the extraction tower, and the acetaldehyde refining tower has the functions of refining acetaldehyde and recovering vinyl acetate. The middle liquid phase of the acetaldehyde refining tower is treated by a middle extraction separator, the acetaldehyde water separated by the middle extraction separator is returned to the acetaldehyde refining tower, the upper layer vinyl acetate liquid separated by the middle extraction separator enters a middle extraction heat exchanger to exchange heat and cool to 5-15 ℃, then enters the top of a collecting tank in the acetaldehyde refining tower, the upper outlet component (namely layered upper layer vinyl acetate liquid) of the collecting tank in the acetaldehyde refining tower enters the lower part of an extraction tower, the tower bottom component of the acetaldehyde refining tower and the bottom outlet component of the collecting tank in the acetaldehyde refining tower enter a sewage treatment system, the tower top component (16-20 ℃) of the acetaldehyde refining tower enters the inlet of a first condenser of the acetaldehyde refining tower, the gas phase outlet component of the first condenser of the acetaldehyde refining tower enters a second condenser of the acetaldehyde refining tower (the temperature is-6 to-3 ℃) after being condensed, and then enters the inlet of the second condenser of the acetaldehyde refining tower to-5 ℃ (the two condensers are arranged, the quantity of one condenser is insufficient), the tower bottom component of the acetaldehyde refining tower bottom component is not less than 98%, and the second condenser is returned to the top of the acetaldehyde refining tower is more than 98%, and the second condenser is returned to the top of the acetaldehyde refining tower (the acetaldehyde is more than 5%), and the distilled off from the other part is more than 98%, and the acetaldehyde is returned to the top of the other condensate tower is more than 98.5%, and the distilled from the top of the acetaldehyde refining tower is qualified.
In the process, the top of the extraction tower adopts synthetic acetaldehyde water (the acetaldehyde water from the synthetic process has the acetaldehyde content of 2-5% and the temperature of 0-10 ℃) as an extractant. The existing extraction tower takes a large amount of desalted water as an extractant to separate acetaldehyde and vinyl acetate, and because the operation temperature of the extraction tower is 5-15 ℃ and the temperature is low, a large amount of chilled water is needed to cool the desalted water (the temperature is 25-35 ℃) to the operation temperature of the extraction tower, otherwise, the extraction effect of the extraction tower is affected; in addition, the use of demineralized water can also result in a significant amount of wastewater being produced at the bottom of the extraction column. The top of the extraction tower adopts synthetic acetaldehyde water (the acetaldehyde content is 2-5% and the temperature is 0-10 ℃) as an extractant, so that the consumption of the desalination water of the extraction tower is reduced, and acetaldehyde in the acetaldehyde synthetic water can be recovered.
In the process, the acetaldehyde water and the vinyl acetate liquid form an interface in the tower due to different densities, and the interface between the acetaldehyde water and the vinyl acetate liquid is controlled at a specified position through an interface regulator in the extraction tower.
In the process, the acetylene tail gas at the top of the extraction tower returns to the synthesis process.
In the process, because the solubility of the vinyl acetate in water is small at low temperature and the acetaldehyde dissolved in the water can be prevented from escaping at low temperature, a jacket is arranged in the extraction tower, chilled water is introduced into the extraction tower for cooling, the lower temperature (5-15 ℃) of the whole tower is maintained, and the selectivity of the water to the acetaldehyde is improved.
In the process, the middle liquid phase of the acetaldehyde refining tower is extracted, the middle liquid phase is separated into upper vinyl acetate layer liquid and lower acetaldehyde layer liquid in a middle extraction separator, the upper vinyl acetate layer liquid is extracted from the middle outlet of the middle extraction separator, the lower acetaldehyde water returns to the acetaldehyde refining tower, the vinyl acetate liquid (the temperature is 30-60 ℃) is cooled to 5-15 ℃ through the chilled water heat exchange in the middle extraction heat exchanger, then enters the middle extraction tank of the acetaldehyde refining tower, and after the middle liquid phase is separated, the upper vinyl acetate layer is pumped into the extraction tower for feeding by the middle extraction pump of the acetaldehyde refining tower. The reason why the middle heat exchanger and the middle groove of the acetaldehyde refining tower are arranged is that: the vinyl acetate upper layer liquid extracted from the middle extraction separator still contains a small amount of acetaldehyde and water, and the high temperature is unfavorable for layering the vinyl acetate and the acetaldehyde water, so that the layering of the vinyl acetate and the acetaldehyde water is required after heat exchange by the middle extraction heat exchanger; the heat exchange is carried out, the temperature is reduced to 5-15 ℃, the mixture enters a collecting tank in an acetaldehyde refining tower, and the upper vinyl acetate layer enters the tower kettle of an extraction tower after layering, so that the temperature of the tower kettle of the extraction tower is reduced from 25-30 ℃ to 10-15 ℃, and the extraction effect of the extraction tower is improved.
In the process, the sewage at the tower kettle of the acetaldehyde refining tower is sent to a sewage treatment system, and the treated sewage is sent to a filtering chamber for boiling and washing the filter for use.
In the process, 1.0-5.0% alkali liquor is added into the feed of the acetaldehyde refining tower, the pH value of the feed is controlled to be 6.5-7.5, the acetaldehyde self-polymerization of the acetaldehyde refining tower is prevented, and the COD of the tower kettle is reduced from 5000-7000 to 1000-3000, so that the sewage of the tower kettle of the acetaldehyde refining tower meets the requirement of being fed into a sewage treatment system.
In the process, the pH value of the synthetic acetaldehyde water is controlled to be 6.5-7.5, so that the synthetic acetaldehyde water is prevented from self-polymerizing, and the extraction effect of the extraction tower is improved.
In the process, the feed of the acetaldehyde refining tower exchanges heat by distilling the gas phase through the vinyl acetate refining tower. The feeding temperature of the acetaldehyde refining tower is 5-15 ℃, the steam consumption is increased by directly feeding, the feeding temperature of the acetaldehyde refining tower is increased to 40-60 ℃ after heat exchange, and the steam consumption of the acetaldehyde refining tower and the circulating water consumption of a condenser of the vinyl acetate refining tower are reduced.
In the process, after the temperature of the liquid extraction in the acetaldehyde refining tower is reduced to 5-15 ℃, the temperature of the extraction tower kettle is reduced to 10-15 ℃ from 25-30 ℃, so that the extraction effect of the extraction tower is improved.
The technical scheme of the invention has the following advantages:
(1) In the acetaldehyde purifying device, the collecting separator with three baffle plates is arranged in the layers 25-30 of the acetaldehyde refining tower, so that the residence time of the middle collecting liquid (namely the middle component of the acetaldehyde refining tower) is prolonged, and the layering effect of the vinyl acetate upper liquid and the acetaldehyde underwater upper liquid is improved; adjusting the layering interface height of the vinyl acetate upper layer liquid and the acetaldehyde water lower layer liquid in the middle-mining separator by arranging an interface adjuster, so that the vinyl acetate upper layer liquid is mined out through an outlet on the middle-mining separator and enters the middle-mining heat exchanger; the middle-extraction separator extracts the upper layer liquid of the vinyl acetate, and the lower layer acetaldehyde water phase returns to the lower layer tower plate of the acetaldehyde refining tower, so that the extraction amount of the acetaldehyde water is reduced, and the energy consumption is reduced; in addition, the vinyl acetate is extracted through the middle liquid phase, so that the phenomenon of tower kettle and tower plate blockage caused by self-polymerization after the vinyl acetate falls into the tower kettle is avoided, and the energy consumption is reduced;
(2) In the acetaldehyde purifying device, the upper layer of vinyl acetate extracted by the middle extraction separator enters the middle extraction heat exchanger and is cooled by chilled water, the temperature is reduced to 5-15 ℃, and after further layering in the distillation tank of the acetaldehyde refining tower, the upper layer of vinyl acetate enters the tower kettle of the extraction tower, the temperature of the tower kettle of the extraction tower is reduced to 10-15 ℃ from 25-30 ℃, so that the extraction effect of the extraction tower is improved;
(3) In the acetaldehyde purifying device, the tower bottom of the acetaldehyde refining tower is directly fed with steam for heating, so that the investment of equipment (reboiler) is reduced, the problem that the reboiler is blocked to influence the stable supply of heat is solved, the stable operation of the acetaldehyde refining tower is ensured, the acetaldehyde refining tower can be preheated in advance before feeding by adopting a direct steam heating mode, the air in the tower is replaced, and the vinyl acetate in the material entering the acetaldehyde refining tower can be prevented from self-polymerization due to lower temperature of the tower bottom when falling into the tower bottom;
(4) In the acetaldehyde purifying device, the top of the extraction tower adopts synthetic acetaldehyde water (the acetaldehyde water from the synthetic process has the acetaldehyde content of 2-5 percent and the temperature of 0-10 ℃) as an extractant, so that the consumption of the desalting water of the extraction tower is reduced, and the acetaldehyde in the acetaldehyde synthetic water can be recovered.
Drawings
In order that the invention may be more readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings, in which:
FIG. 1 is a schematic view showing the construction of an acetaldehyde purifying apparatus in example 1 of the present invention,
FIG. 2 is an enlarged view showing the internal structure of the intermediate recovery separator in example 1 of the present invention,
wherein: 1-extraction tower, 2-acetaldehyde refining tower, 3-middle collecting separator, 4-middle collecting heat exchanger, 5-acetaldehyde refining tower middle collecting tank, 6-acetaldehyde refining tower first condenser, 7-acetaldehyde refining tower second condenser, 8-acetaldehyde refining tower distillation tank, 9-vinyl acetate refining tower condenser, 10-sewage treatment system, 11-pipe cap, 12-first baffle plate, 13-second baffle plate and 14-third baffle plate.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "provided," "connected," and the like are to be construed broadly, and may be fixedly connected, detachably connected, or integrally connected, for example; the two components can be mechanically connected, can be directly connected or can be indirectly connected through an intermediate medium, and can be communicated with each other. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
As shown in FIG. 1, the acetaldehyde purifying apparatus of the present invention comprises: an extraction tower 1, an acetaldehyde refining tower 2, an acetaldehyde refining tower first condenser 6, an acetaldehyde refining tower second condenser 7, an acetaldehyde refining tower distillation tank 8, an acetaldehyde refining tower middle extraction tank 5, a sewage treatment system 10, a middle extraction separator 3 and a middle extraction heat exchanger 4;
the method comprises the steps that a top distillate pipeline of a vinyl acetate crude separation tower is connected with a lower inlet of an extraction tower 1, an upper inlet of the extraction tower 1 is connected with a synthetic acetaldehyde water pipeline, a bottom outlet of the extraction tower 1 is connected with a (middle) inlet of an acetaldehyde refining tower 2, an upper outlet extraction tower recovery liquid pipeline of the extraction tower 1 is connected with an inlet of the vinyl acetate crude separation tower, a top outlet of the acetaldehyde refining tower 2 is connected with an inlet of an acetaldehyde refining tower first condenser 6, a bottom outlet of the acetaldehyde refining tower 2 is connected with a sewage treatment system 10, a gas phase outlet of the acetaldehyde refining tower first condenser 6 is connected with an inlet of an acetaldehyde refining tower second condenser 7, a condensate outlet pipeline of the acetaldehyde refining tower first condenser 6 is connected with an inlet of an acetaldehyde refining tower distillate tank 8 after being converged, one path of the condensate outlet pipeline is connected with the acetaldehyde pipeline, the other path of the condensate outlet is returned to the top of the acetaldehyde refining tower 2, a middle separator 3 is arranged in the middle of the acetaldehyde refining tower 2, a gas phase outlet of the middle separator 3 is connected with an inlet of the lower layer 2 of the acetaldehyde refining tower, a condensate outlet of the acetaldehyde refining tower first condenser 6 is connected with an inlet of the acetaldehyde refining tower 5, and a condensate outlet of the acetaldehyde refining tower is connected with an upper layer 5 of the acetaldehyde refining tower, and the condensate outlet of the condensate tower is connected with an inlet of the acetaldehyde refining tower 5.
In another preferred embodiment, the bottom of the acetaldehyde refining column 2 is connected to a vapor feed line.
In a further preferred embodiment, the intermediate recovery separator 3 is arranged at the 25 th to 30 th trays, preferably at the 29 th to 30 th trays, of the acetaldehyde refining column 2.
In another preferred embodiment, as shown in FIG. 2, a pipe cap 11 is arranged at the 29 th-30 th tower plate of the acetaldehyde refining column 2, a circle of pipe cap 11 is welded with the acetaldehyde refining column 3 in a sealing way, and a separator 3 is adopted in an opening welding connection at one side of the column wall connected with the welding part of the acetaldehyde refining column 2.
In a further preferred embodiment, the height of the intermediate recovery separator 3 is 800-1000mm, for example about 912mm. Preferably, as shown in fig. 2, the middle-mining separator 3 adopts three baffles, the first baffle 12 is arranged at the top of the inner side of the middle-mining separator 3, the second baffle 13 is arranged at the bottom of the inner side of the middle-mining separator 3, the third baffle 14 is arranged at the top of the inner side of the middle-mining separator 3, and the second baffle 13 is intersected with the first baffle 12 and the third baffle 14; preferably, the first baffle 12, the second baffle 13 and the third baffle 14 are all vertically arranged. A pipe cap 11 is arranged between 25 layers and 30 layers of the acetaldehyde refining tower 2, the lower end of the pipe cap 11 is completely welded with the acetaldehyde refining tower 2, one side of the tower wall adjacent to the welding position is provided with a middle-layer separator 3 in a welded connection, ascending air flow enters 30 layers of tower plates for example through the pipe cap 11, after condensed liquid is layered through the middle-layer separator 3, retention time is prolonged through baffle plates, upper-layer vinyl acetate liquid and acetaldehyde water are conveniently layered, interface height is adjusted through a middle-layer interface regulator, lower-layer water phase (the acetaldehyde water) flows back to the acetaldehyde refining tower 2 (for example, 29 layers of tower plates) through an acetaldehyde water outlet (flange mouth pipeline), and upper-layer vinyl acetate is connected with an inlet of the middle-layer heat recovery exchanger 4 through an ethyl acetate upper-layer liquid outlet.
In a further preferred embodiment, chilled water is introduced into the intermediate heat exchanger 4.
In another preferred embodiment, the bottom outlet of the extraction column 1 is connected to the inlet of the acetaldehyde refining column 2 after passing through a heat exchanger. The heat exchanger is preferably a condenser 9 of a vinyl acetate refining tower so as to utilize the waste heat of the gas phase distilled from the vinyl acetate refining tower. Namely: the gas phase discharge pipeline of the top of the vinyl acetate refining tower is connected with the upper inlet of the vinyl acetate refining tower condenser 9, the condensate outlet of the vinyl acetate refining tower condenser 9 is connected with the discharge pipeline of the vinyl acetate condensate, the lower inlet of the vinyl acetate refining tower condenser 9 is connected with the bottom outlet of the extraction tower 1, and the upper outlet of the vinyl acetate refining tower condenser 9 is connected with the inlet of the acetaldehyde refining tower 2.
Example 1
As shown in fig. 1, the acetaldehyde purifying apparatus of the present embodiment includes: an extraction tower 1, an acetaldehyde refining tower 2, an acetaldehyde refining tower first condenser 6, an acetaldehyde refining tower second condenser 7, an acetaldehyde refining tower distillation tank 8, an acetaldehyde refining tower middle extraction tank 5, a sewage treatment system 10, a middle extraction separator 3 and a middle extraction heat exchanger 4; the method comprises the steps of connecting a top distillate pipeline of a vinyl acetate crude separation tower with a lower inlet of an extraction tower 1, connecting an upper inlet of the extraction tower 1 with a synthetic acetaldehyde water pipeline, connecting a bottom outlet of the extraction tower 1 with a middle inlet of an acetaldehyde refining tower 2, connecting an upper outlet of the extraction tower with a recovery liquid pipeline of the extraction tower 1 with an inlet of the vinyl acetate crude separation tower, connecting a top outlet of the acetaldehyde refining tower 2 with an inlet of a first condenser 6 of the acetaldehyde refining tower, connecting a bottom outlet of the acetaldehyde refining tower 2 with a sewage treatment system 10, connecting a gas phase outlet of the first condenser 6 of the acetaldehyde refining tower with an inlet of a second condenser 7 of the acetaldehyde refining tower, connecting a condensate outlet pipeline of the first condenser 6 of the acetaldehyde refining tower with a condensate outlet pipeline of the second condenser 7 with an inlet of an acetaldehyde refining tower distillate tank 8 after merging, connecting an outlet pipeline of the acetaldehyde refining tower 8 with an acetaldehyde product pipeline, connecting the other pipeline back to the top of the acetaldehyde refining tower 2, arranging a middle separator 3 at a 30 th layer tower plate of the acetaldehyde refining tower 2, connecting a gas phase outlet of the middle separator 3 with an inlet of the second condenser 4 of the acetaldehyde refining tower 2, connecting a liquid outlet of the middle separator 3 with an upper separator 5 of the acetaldehyde refining tower 5, and connecting a bottom inlet of the water separator 4 of the acetaldehyde refining tower 2 with an upper separator 5 of the water separator 5 of the extraction tower 2, and connecting a bottom inlet of the water separator 5 of the extraction tower 2.
As shown in FIG. 2, a pipe cap 11 is arranged at the 30 th column plate of the acetaldehyde refining column 2, one circle of pipe cap 11 bottom is welded with the acetaldehyde refining column 2 in a sealing way, and one side of the column wall connected with the welding part of the acetaldehyde refining column 2 is welded with the middle separator 3.
Wherein, the tower bottom of the acetaldehyde refining tower 2 is connected with a steam inlet pipeline.
The middle-mining separator 3 is 912mm in height, as shown in fig. 2, the middle-mining separator 3 adopts three baffles, a first baffle 12 is arranged at the top of the inner side of the middle-mining separator 3, a second baffle 13 is arranged at the bottom of the inner side of the middle-mining separator 3, a third baffle 14 is arranged at the top of the inner side of the middle-mining separator 3, and the second baffle 13 is crossed with the first baffle 12 and the third baffle 14; the first baffle plate 12, the second baffle plate 13 and the third baffle plate 14 are all arranged vertically.
Wherein, the middle mining separator 3 is internally provided with an interface regulator.
Wherein chilled water is introduced into the middle heat exchanger 4.
Wherein, the bottom outlet of the extraction tower 1 is connected with the inlet of the acetaldehyde refining tower 2 after passing through a heat exchanger. The heat exchanger is preferably a condenser 9 of a vinyl acetate refining tower so as to utilize the waste heat of the gas phase distilled from the vinyl acetate refining tower. Namely: the gas phase discharge pipeline of the top of the vinyl acetate refining tower is connected with the upper inlet of the vinyl acetate refining tower condenser 9, the condensate outlet of the vinyl acetate refining tower condenser 9 is connected with the discharge pipeline of the vinyl acetate condensate, the lower inlet of the vinyl acetate refining tower condenser 9 is connected with the bottom outlet of the extraction tower 1, and the upper phase outlet of the vinyl acetate refining tower condenser 9 is connected with the inlet of the acetaldehyde refining tower 2.
The device is adopted to purify the acetaldehyde in the reaction liquid and the filtered clear liquid synthesized by the acetylene method of calcium carbide according to the following process:
the reaction liquid (component: 45-50% of acetic acid, 45-50% of vinyl acetate, 1.0-2.5% of acetaldehyde, 0.8-1.8% of acetylene, 0.01-0.1% of water, a small amount of carbon powder and zinc acetate, the temperature is 10-40 ℃), and filtering clear liquid (components: 85-95% of acetic acid, 5-10% of vinyl acetate, 0.01-0.1% of water, carbon powder containing carbon and zinc acetate, and the temperature of 85-95 ℃ are rectified by a vinyl acetate rough separation tower to obtain a vinyl acetate rough separation tower top distillate (containing 85-95% of vinyl acetate, 5-10% of acetaldehyde, 1.0-2.0% of a small amount of water and the like, the temperature of 5-15 ℃) and then the vinyl acetate rough separation tower top distillate enters the lower part of an extraction tower 1 (the extraction tower 1 is used for primarily separating acetaldehyde from vinyl acetate, the feeding of the raw materials comprises the vinyl acetate rough separation tower distillate (the temperature is 5-15 ℃, 85-95% of vinyl acetate, 5-10% of acetaldehyde, 1.0-2.0% of a small amount of water and the like) and a vinyl acetate upper liquid (the temperature is 40-60 ℃, the content of the vinyl acetate is 60-80%, the content of the acetaldehyde is 10-20% and the content of the water is 5-10% and the like) which is extracted by a separator in an acetaldehyde refining tower and subjected to heat exchange with a middle heat exchanger, wherein an extractant is added into the top inlet of the extraction tower 1 to synthesize acetaldehyde water (low-temperature acetaldehyde water from a synthetic water washing tower, the acetaldehyde content is 2-5% and the temperature is 0-10 ℃), because acetaldehyde can be mixed with water, the solubility of the acetaldehyde in the vinyl acetate and the solubility of the vinyl acetate in the water are very low, a distillate of a vinyl acetate crude separation tower is added from the lower part of the extraction tower 1, the density of the vinyl acetate is small and moves upwards, the acetaldehyde is gradually dissolved in the acetaldehyde water added from the upper part of the tower, the density is large, the two materials move downwards, alternately pass through the packing in the tower and are in countercurrent contact, and the acetaldehyde gradually diffuses into the water and falls on the lower part of the tower. After extraction, the bottom component (component: 80-90% of water, 5.0-10.0% of acetaldehyde, 1.0-5.0% of vinyl acetate and 5-15 ℃ of temperature, wherein the distilled gas phase of the vinyl acetate refining tower enters the middle part of an acetaldehyde refining tower 2 after heat exchange in a condenser 9 of the vinyl acetate refining tower and the feeding temperature is increased to 40-60 ℃, and the tower top components (components: 80-90% of vinyl acetate, 1.0-5.0% of acetaldehyde, 0.5-1.5% of water and 5-15 ℃ as recovery liquid of an extraction tower, wherein the middle liquid phase of the acetaldehyde refining tower 2 is extracted by a middle extraction separator 3 (35-60 ℃) and returns to the acetaldehyde refining tower 2 after layering, the upper layer of the acetic acid liquid enters a middle extraction heat exchanger 4 for heat exchange and cooling to 5-15 ℃ (the effect of the acetaldehyde refining tower 2 is to refine acetaldehyde and recover vinyl acetate), then enters the top of a extraction tank 5 in the acetaldehyde refining tower, the upper outlet component of the extraction tank 5 in the acetaldehyde refining tower (namely the layered upper layer of acetic acid) enters the lower part of the extraction tower 1, the tower kettle component of the acetaldehyde refining tower 2 and the bottom outlet component of the extraction tank 5 in the acetaldehyde refining tower enter a sewage treatment system 10, the tower top component (16-20 ℃) of the acetaldehyde refining tower 2 enters the upper inlet of a first condenser 6, after freezing water (the temperature is-6 to-3 ℃) is condensed, the gas phase component of the first condenser 6 enters the second condenser (the second condenser 7 ℃ to the inlet of the acetaldehyde condenser 5 ℃ in the second condenser 7), the condensate outlet component (refined acetaldehyde, acetaldehyde is more than or equal to 98.5 percent and at minus 5-5 ℃) of the second condenser 7 of the acetaldehyde refining tower and the condensate outlet component of the first condenser 6 of the acetaldehyde refining tower are converged and then enter the distillation tank 8 of the acetaldehyde refining tower, a part of qualified acetaldehyde (acetaldehyde is more than or equal to 98.5 percent) at the bottom outlet of the distillation tank 8 of the acetaldehyde refining tower can be sent out for sale, unqualified acetaldehyde (acetaldehyde is less than 98.5 percent) can be returned to the acetaldehyde refining tower 2 for reprocessing, and the other part of the qualified acetaldehyde is returned to the top of the acetaldehyde refining tower 2 for reflux.
As can be seen from example 1, in the acetaldehyde purifying apparatus of this embodiment, by setting the height of the middle-mining separator and the baffle plate, the residence time of the middle-mining liquid is increased, the layering effect is improved, the middle-mining separator extracts the upper layer liquid of vinyl acetate, the lower layer water phase (acetaldehyde water) returns to the lower layer tray of the acetaldehyde refining tower, the extraction amount of the acetaldehyde water is reduced by about 20000 t/year, so that the energy consumption is reduced, for example, the steam consumption is reduced to 2000-3000 t/year, and the acetaldehyde separating effect of the acetaldehyde refining tower is also improved; in addition, the recovery of the vinyl acetate with the amount of 5000-5500 t/year can be realized by adopting the liquid phase to extract the vinyl acetate, and the phenomenon of tower kettle and tower plate blockage caused by self-polymerization after the vinyl acetate falls into the tower kettle of the acetaldehyde refining tower is avoided, so that the energy consumption is reduced, for example, the steam consumption is reduced to 3000-4000 t/year. The temperature of the liquid extraction in the acetaldehyde refining tower is reduced to 5-15 ℃ by a middle heat exchanger, the temperature of the extraction tower kettle is reduced to 10-15 ℃ from 25-30 ℃, and the extraction effect of the extraction tower is improved; the tower bottom of the acetaldehyde refining tower is directly fed with steam for heating, so that the problem that the heat stability is affected by the blockage of a reboiler is solved, the stable operation of the acetaldehyde refining tower is ensured, the equipment investment is reduced, if the reboiler is used for heating, the acetaldehyde refining tower cannot normally and stably operate, when the blockage occurs, the acetaldehyde refining tower needs to be boiled and washed by adding caustic soda slices, the cleaning is carried out for at least 24 hours, and the operation has great safety risk; the top of the extraction tower adopts synthetic acetaldehyde water (the acetaldehyde content is 2-5% and the temperature is 0-10 ℃) as an extractant, so that the consumption of the desalination water of the extraction tower is reduced by 70000-80000 t/year, and the acetaldehyde in the acetaldehyde synthetic water can be recovered, and the recovered acetaldehyde amount is 1700-2000 t/year.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.
Claims (17)
1. An acetaldehyde purification apparatus, comprising: an extraction tower (1), an acetaldehyde refining tower (2), an acetaldehyde refining tower middle extraction tank (5), a middle extraction separator (3) and a middle extraction heat exchanger (4);
the lower inlet of the extraction tower (1) is connected with a raw material feeding pipeline, the upper inlet of the extraction tower (1) is connected with an extractant pipeline, the bottom outlet of the extraction tower (1) is connected with the inlet of the acetaldehyde refining tower (2), the upper outlet of the extraction tower (1) is connected with an extraction tower recovery liquid pipeline, the top outlet pipeline of the acetaldehyde refining tower (2) is divided into two paths, one path is connected with the acetaldehyde pipeline, the other path returns to the top of the acetaldehyde refining tower (2), the middle part of the acetaldehyde refining tower (2) is provided with a middle-collecting separator (3), the lower water phase outlet of the middle-collecting separator (3) returns to the acetaldehyde refining tower (2), the vinyl acetate liquid outlet of the middle-collecting separator (3) is connected with the inlet of the middle-collecting heat exchanger (4), the outlet of the middle-collecting heat exchanger (4) is connected with the top inlet of the middle-collecting tank (5) of the acetaldehyde refining tower, and the upper outlet pipeline of the middle-collecting tank (5) of the acetaldehyde refining tower is connected with the lower inlet of the extraction tower (1);
the middle-collecting separator (3) is arranged at the 25 th-30 th column plate of the acetaldehyde refining column (2); the middle-mining separator (3) adopts three baffle plates, a first baffle plate (12) is arranged at the top of the inner side of the middle-mining separator (3), a second baffle plate (13) is arranged at the bottom of the inner side of the middle-mining separator (3), a third baffle plate (14) is arranged at the top of the inner side of the middle-mining separator (3), and the second baffle plate (13) is crossed with the first baffle plate (12) and the third baffle plate (14);
the raw material feeding pipeline is connected with the tower top distillate pipeline of the vinyl acetate crude separation tower.
2. The device according to claim 1, wherein a pipe cap (11) is further arranged at the 25 th-30 th tower plate of the acetaldehyde refining tower (2), a circle of pipe cap (11) is connected with the acetaldehyde refining tower (2) in a sealing way, and a middle separator (3) is connected with one side opening of the tower wall connected with the connection part of the acetaldehyde refining tower (2).
3. The apparatus according to claim 2, characterized in that the height of the middling separator (3) is 800-1000mm.
4. A device according to claim 3, characterized in that the first baffle (12), the second baffle (13) and the third baffle (14) are all arranged vertically.
5. The device according to claim 1, characterized in that an interface regulator is provided in the intermediate separator (3).
6. The device according to claim 1, characterized in that chilled water is introduced into the intermediate heat exchanger (4).
7. The apparatus according to claim 1, wherein the bottom of the acetaldehyde refining column (2) is connected to a steam inlet line.
8. The device according to claim 1, characterized in that the extractant line in the upper part of the extraction column (1) is connected to the synthesis acetaldehyde line; and/or the bottom outlet of the extraction tower (1) is connected with the inlet of the acetaldehyde refining tower (2) after passing through the heat exchanger.
9. The apparatus according to claim 8, wherein the heat exchanger is a vinyl acetate finishing column condenser (9); the gas phase discharge pipeline of the top of the vinyl acetate refining tower is connected with the upper inlet of the vinyl acetate refining tower condenser (9), the condensate outlet of the vinyl acetate refining tower condenser (9) is connected with the discharge pipeline of the vinyl acetate condensate, the lower inlet of the vinyl acetate refining tower condenser (9) is connected with the bottom outlet of the extraction tower (1), and the upper outlet of the vinyl acetate refining tower condenser (9) is connected with the inlet of the acetaldehyde refining tower (2).
10. The apparatus of claim 1, wherein the extraction column recovery line is connected to a vinyl acetate crude feed inlet.
11. The apparatus according to any one of claims 1-10, further comprising: an acetaldehyde refining tower first condenser (6), an acetaldehyde refining tower second condenser (7) and an acetaldehyde refining tower distillation tank (8); the top outlet of the acetaldehyde refining tower (2) is connected with the inlet of a first condenser (6) of the acetaldehyde refining tower, the bottom outlet of the acetaldehyde refining tower (2) is connected with a sewage treatment system (10), the gas phase outlet of the first condenser (6) of the acetaldehyde refining tower is connected with the inlet of a second condenser (7) of the acetaldehyde refining tower, the condensate outlet pipeline of the first condenser (6) of the acetaldehyde refining tower is connected with the condensate outlet pipeline of the second condenser (7) of the acetaldehyde refining tower and the inlet of a distillation tank (8) of the acetaldehyde refining tower, the outlet pipeline of the distillation tank (8) of the acetaldehyde refining tower is divided into two paths, one path is connected with the acetaldehyde pipeline, the other path returns to the top of the acetaldehyde refining tower (2), and the bottom outlet of a collecting tank (5) in the acetaldehyde refining tower is connected with the sewage treatment system (10).
12. An acetaldehyde purification process, comprising the steps of:
the method comprises the steps that raw materials enter the lower part of an extraction tower (1), an extracting agent is added into the top inlet of the extraction tower (1), after extraction, tower bottom components of the extraction tower (1) enter the middle part of an acetaldehyde refining tower (2), middle liquid phases of the acetaldehyde refining tower (2) are extracted through a middle extraction separator (3), lower-layer acetaldehyde water returns to the acetaldehyde refining tower (2) after layering, upper-layer vinyl acetate liquid enters a middle extraction heat exchanger (4) for heat exchange and cooling to 5-15 ℃, then enters the top of a middle extraction groove (5) of the acetaldehyde refining tower, upper-part outlet components of the middle extraction groove (5) of the acetaldehyde refining tower enter the lower part of the extraction tower (1), the tower top components of the acetaldehyde refining tower (2) are divided into two parts, one part of the components are extracted, and the other part of the components returns to the top of the acetaldehyde refining tower (2) for reflux;
the middle-collecting separator (3) is arranged at the 25 th-30 th column plate of the acetaldehyde refining column (2); the middle-mining separator (3) adopts three baffle plates, a first baffle plate (12) is arranged at the top of the inner side of the middle-mining separator (3), a second baffle plate (13) is arranged at the bottom of the inner side of the middle-mining separator (3), a third baffle plate (14) is arranged at the top of the inner side of the middle-mining separator (3), and the second baffle plate (13) is crossed with the first baffle plate (12) and the third baffle plate (14);
the distillate at the top of the vinyl acetate crude separation tower is taken as a raw material to enter the lower part of the extraction tower (1).
13. The process according to claim 12, wherein the bottom component of the extraction column (1) and the distillation gas phase of the vinyl acetate refining column are fed into the middle part of the acetaldehyde refining column (2) after heat exchange in the vinyl acetate refining column condenser (9) and the temperature is increased to 40-60 ℃.
14. Process according to claim 12 or 13, characterized in that the top inlet of the extraction column (1) is fed with an extractant to synthesize acetaldehyde water.
15. Process according to claim 12 or 13, characterized in that the overhead component of the extraction column (1) is fed as extraction column recovery to the vinyl acetate crude column.
16. The process according to claim 12 or 13, wherein the reaction solution of synthesizing vinyl acetate by the acetylene method is rectified by a vinyl acetate crude separation tower to obtain a top distillate of the vinyl acetate crude separation tower.
17. The process according to claim 12 or 13, wherein the bottom outlet component of the collecting tank (5) in the acetaldehyde refining column (2) and the bottom outlet component of the collecting tank in the acetaldehyde refining column are both introduced into the sewage treatment system (10), the top component of the acetaldehyde refining column (2) is introduced into the upper inlet of the first condenser (6) of the acetaldehyde refining column, after condensation of chilled water, the gas phase outlet component of the first condenser (6) of the acetaldehyde refining column is introduced into the inlet of the second condenser (7) of the acetaldehyde refining column, the condensate outlet component of the second condenser (7) of the acetaldehyde refining column and the condensate outlet component of the first condenser (6) of the acetaldehyde refining column are combined and introduced into the distillation tank (8), and a part of the acetaldehyde is extracted from the bottom outlet of the distillation tank (8) of the acetaldehyde and the other part is returned to the top of the acetaldehyde refining column (2) for reflux.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN206418054U (en) * | 2016-12-28 | 2017-08-18 | 宁夏大地循环发展股份有限公司 | Avoid emptying formula rectifying column tail gas recycle reutilization system |
Non-Patent Citations (3)
| Title |
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| 巫传英 ; 夏素兰 ; 刘红卫 ; .醋酸乙烯装置乙醛精馏塔中乙醛聚合原因分析及改造措施.天然气化工(C1化学与化工).2009,(03),63-66. * |
| 牛杰 ; .乙醛精制系统的工艺优化.现代化工.2017,(02),151-154. * |
| 罗静.醋酸乙烯精馏装置的工艺流程模拟与优化.中国优秀硕士学位论文全文数据库工程科技Ⅰ辑.2018,(第08期),B016-2. * |
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| CN114195628A (en) | 2022-03-18 |
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